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Exhaustively match over all alias kinds

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This commit is contained in:
Oli Scherer 2023-03-07 10:21:20 +00:00
parent 669e751639
commit d3d537b972
2 changed files with 29 additions and 20 deletions
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27
compiler/rustc_trait_selection/src/traits/query/normalize.rs
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@ -197,23 +197,30 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>
return Ok(*ty);
}
let (kind, data) = match *ty.kind() {
ty::Alias(kind, data) => (kind, data),
_ => {
let res = ty.try_super_fold_with(self)?;
self.cache.insert(ty, res);
return Ok(res);
}
};
// See note in `rustc_trait_selection::traits::project` about why we
// wait to fold the substs.
// Wrap this in a closure so we don't accidentally return from the outer function
let res = match *ty.kind() {
let res = match kind {
// This is really important. While we *can* handle this, this has
// severe performance implications for large opaque types with
// late-bound regions. See `issue-88862` benchmark.
ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. })
if !substs.has_escaping_bound_vars() =>
{
ty::Opaque if !data.substs.has_escaping_bound_vars() => {
// Only normalize `impl Trait` outside of type inference, usually in codegen.
match self.param_env.reveal() {
Reveal::UserFacing => ty.try_super_fold_with(self)?,
Reveal::All => {
let substs = substs.try_fold_with(self)?;
let substs = data.substs.try_fold_with(self)?;
let recursion_limit = self.interner().recursion_limit();
if !recursion_limit.value_within_limit(self.anon_depth) {
// A closure or generator may have itself as in its upvars.
@ -228,7 +235,7 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>
return ty.try_super_fold_with(self);
}
let generic_ty = self.interner().type_of(def_id);
let generic_ty = self.interner().type_of(data.def_id);
let concrete_ty = generic_ty.subst(self.interner(), substs);
self.anon_depth += 1;
if concrete_ty == ty {
@ -248,7 +255,9 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>
}
}
ty::Alias(ty::Projection, data) if !data.has_escaping_bound_vars() => {
ty::Opaque => ty.try_super_fold_with(self)?,
ty::Projection if !data.has_escaping_bound_vars() => {
// This branch is just an optimization: when we don't have escaping bound vars,
// we don't need to replace them with placeholders (see branch below).
@ -297,7 +306,7 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>
}
}
ty::Alias(ty::Projection, data) => {
ty::Projection => {
// See note in `rustc_trait_selection::traits::project`
let tcx = self.infcx.tcx;
@ -353,8 +362,6 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>
res
}
}
_ => ty.try_super_fold_with(self)?,
};
self.cache.insert(ty, res);